Objectives for the next year are: (1)\Finish the purification of the serum factor which induces human monocyte maturation. (2)\Determine the ability of the serum factor to induce increased cytolytic activity by human monocytes and to induce the ability of human monocytes to phagocytose C3 coated particles. The techniques to be employed in the factor purification include affinity chromatography using anti-human serum albumin antibody linked to Affi Gel 10, chromatofocusing, and extraction with methanol and other organic solvents. The starting material will be the human serum albumin fraction obtained by ammonium sulfate precipitation and precipitation at pH 4. Purification will be monitored by the ability of newly developed fractions to induce lysosomal enzyme activity in monocytes cultured for 5-7 days. The ability of this serum factor to induce functional changes will be examined by measuring the cytolytic activity and phagocytosis of C3 coated particles in monocytes cultured in the serum factor. Lysis and release of 51Cr from labelled K562 cells will be used as a measure of cytolytic activity. Uptake of C3-coated sheep erythrocytes will be utilized to assess the ability of monocytes, cultured in the serum factor to phagocytose C3 coated particles. The coated erythrocytes will be labelled with 51Cr. Followingthe removal of noningested erythrocytes by gentle washing and treatment with ammonium chloride, the 51Cr remaining associated with the phagocytes will be transferred to a tube by lysing the cells with Triton X-100. These lysates will be counted in a gamma-counter. Parallel cultures of monocytes, cultured under the same conditions but not receiving erythrocytes will be utilized to determine the number of adherent monocytes. The number of erythrocytes ingested per phagocyte will be calculated. A microtiter culture system will be established. This will allow for evaluation of activities in triplicate cultures and for the measurement of activities of monocytes cultured in 3-4 concentrations of serum or serum factors in the same experiment. By comparing activities in the same experiment and calculating the ED50 of each inducing agent, the relative activities can be more accurately determined. This comparison is not currently possible because of the number of cells required per large culture well and the limited number of cells obtained from a donor. (MB)